1. Field of the Invention
The present invention relates to a micro cooling device for discharging out unnecessary heat, and more particularly to a micro cooling device for an electronic product that generates unnecessary heat in spite of a small size of product, such as an integrated circuit device.
2. Brief Description of the Prior Art
Due to a large quantity of heat generated by an integrated circuit device like a recently developed central processing unit (CPU), the device itself and a system containing it tend to be degenerated in product reliability. Especially, in a semiconductor device, a variety of parameters are affected by the operation temperature so that their values are changed, thereby causing a problem in the device to deteriorate performances of the integrated circuit.
One representative conventional method to solve the aforementioned problem is using a fan to forcibly cool down the device. However, the aforementioned method has its own problems like a low cooling efficiency, introduction of additional heat generating source, such as a power source for the fan, and additional heat generated by the fan itself.
Another method having a higher cooling efficiency is discharging heat by changing phases of a liquid material(xe2x80x9ccoolantxe2x80x9d). In other words, a liquid material used as a coolant is passing over a heat generating source and turning into gas to discharge heat with its vaporizing energy, which has been widely used in refrigerators and air conditioners. There is also a problem in the aforementioned method in that a variety of equipment should be additionally installed for condensing the vaporized(or gaseous) coolant, so that the bulkiness of the total system and power consumption are increased.
Recently, a very small-sized cooling device, so called a heat pipe, has been developed by applying phase changes of a liquid material and natural convection phenomenon. Even if there are a various types of heat pipes, a double-pipe type of heat pipe having internal and external pipes is introduced as an efficient cooling device. In the double-pipe type, the coolant is filled in the external pipe, and the wall of the internal pipe has a plurality of fine holes to form a passage to the external pipe from the inside of the internal pipe. When heat from a heat source is transferred to the external pipe, the coolant in the external pipe turns into gas by absorbing the heat, and the vaporized coolant is infused into the inside of internal pipe through the holes on the internal pipe. The gas in the internal pipe further moves to the opposite end of the internal pipe through differences in buoyancy and air pressure. At the opposite end of the internal pipe, the coolant is condensed into liquid. The liquid moves through the holes of the internal pipes to the external pipe and finally returns to the original place of the coolant.
The heat pipe made in the aforementioned principle is small and has a favorable cooling efficiency. However, as the movement of the gas coolant inside the pipe is dependent on differences in buoyancy and air pressure and the movement of the liquid coolant is dependent on gravity, there is a limitation on the installation position or place of the heat pipe. Furthermore, since the heat pipe should be constructed in a structure in which the coolant is condensed at the opposite end of the heat generating source, as the size of the heat pipe gets smaller, its cooling efficiency gets lower and its performance gets poorer.
Therefore, it is an object of the present invention to solve the aforementioned problems of the conventional cooling devices and to provide a micro cooling device which can be made very small, but with high cooling performances.
In addition, it is another object of the present invention to provide a cooling device of high efficiency that has no restriction in installation position or place which is not influenced by gravity.
In order to accomplish the aforementioned objects of the present invention, there is provided a cooling device which discharges out heat generated by a heat generating source, said device comprising: a coolant storing part for storing liquid coolant; a heat absorbing part comprising at least one micro channel and being positioned to be close to said heat generating source and connected to said coolant storing part, said liquid coolant being partly filled in said micro channel by surface tension and vaporized to be gaseous coolant in said micro channel when heat is absorbed from said heat generating source; a heat insulating part being adjacent to said heat absorbing part for preventing said heat absorbed by said heat absorbing part from transferring to other zones; a condensing part for condensing said gaseous coolant and being positioned apart from said heat absorbing part; a gas moving part being close to said heat absorbing part and said condensing part and being a passage through which said gaseous coolant moves from said heat absorbing part to said condensing part; and a housing in which at least said heat absorbing part is comprised.